Refrigerant control means



' July 28, 1959 Filed March 18. 1958 INVENTOR. LEONARD w. ATCH :sow

' HIS ATTORNEY UnitedStates Patent REFRIGERANT CONTROL Leonard W.Atchison, Louisville, Ky., assignor to General Electric Company, acorporation of New York Application March 18, 1958, Serial No. 722,181

'1 Claim. (c1. 62-197 improved arrangement for reducing the quantity ofre frigerant pumped by the compressor when the pressure on the highpressure side of the system exceeds a predetermined value.

It is an object of the present invention to provide, for a refrigeratingsystem using a capillary expansion means between the high and lowpressure sides of the system, an improved arrangement for automaticallymodulating the flow of refrigerant through the system when the pressureon the high side of the system exceeds a predetermined maximum. t

It is afurther object of the present invention to provide, in arefrigeration system using a capillary expansion means between the highand low pressure sides of the system and utilizing outdoor air forcoolingthe condenser of the system, a liquid refrigerant flow controland storing arrangementfor automatically reducing the amount ofrefrigerant flowing through the system as the outdoor temperatureincreases and reduces the amount of refrigerant gas that can beeffectively liquified in the condenser of the system.

Further objects and advantages of the invention will" become apparent asthe following description proceeds, and the features of novelty whichcharacterize the invention will be pointed outwith particularity in theclaim annexed to and forming a part of this specification.

In accordance with the present invention there is provided a closedrefrigerant. circuit in which are arranged a compressor, a condensingmeans, and an evaporator. A flow control restrictor between thecondensing means and the evaporator is provided in the form of first andsecond capillaries connected in series relationship and having anintermediate chamber arranged therebetween.

In order to vary the flow of refrigerant through the system, a bypassconduit is connected between the .condensing means and the intermediatechamber for introducing gaseous refrigerant from the condensing meansinto the intermediate chamber and thereby into the second capillary. Apressure responsive means associated compressor 3 and a condensing meanswhich condenses and stores liquid refrigerant. In the illustrated embodi2,89%,422 Patented July 28, 1959 ice ment of the invention, thecondensing means includes a condenser 4 and a receiver 8 for storingrefrigerant liquified in the condenser. However, it is possible with acondenser of proper proportions to provide this storing function in thelater stages'of the condenser.

The operation of the compressor withdraws gaseous refrigerant from theevaporator through a suction line 6 and delivers hot compressed gaseousrefrigerant to the condenser 4 through a discharge line 7. The hotcompressed refrigerant in the condenser 4 is cooled by circulating acooling medium, such as air, over the surface of the condenser thusliquifying the refrigerant within the condenser which then flows into aliquid receiver 8 where it is stored prior to passing through theremaining components of the system.

Liquid refrigerant is. delivered from. the receiver 8 through acapillary expansion means to the evaporator 2. Where the liquidrefrigerant evaporates under reduced pressure. More specifically, thecapillary expansion means of the present invention includes a firstcapillary 9 and a second capillary 11 connected in series circuitbetween the lower portion of the receiver 8 and the end of theevaporator 2. Obviously, if the storing of liquid refrigerant isperformed by the later stages of the condenser 4, then the capillary 9would connect directly to the condenser 4. The capillaries 9 and 11 areseparated by a small intermediate chamber 12 which, in the illustratedembodiment of the invention, is formed as an integral portion of themain receiver body 8. This intermediate chamber 12 could be remotelydisposed or separated from the receiver 8 or from the condenser as longas the chamber is connected between the first and second capillaries inthe manner explained above. During normal. operation of the system, therefrigerant liquid flows from the lower portion of the receiver 8through the capillary 9, and enters the chamber 12 which is ofrelatively small dimensions. Normally, the refrigerant passing throughchamber 12 is largely in the liquified phase. Liquid refrigerant thenenters the capillary 11 whereupon it is delivered to the end of theevaporator 2. A pressure drop caused by the capillary 9 exists undernormal conditions of operation, between the receiver 8 and theintermediate chamber 12 as well as between the chamber 12 and theevaporator 2.

The term high pressure side as employed in this specification hasreference to what is commonly called a highside and which comprises thecomponents of the system in the refrigerant circuit from the compressorto the flow restrictor means, or more specifically to the capillary 9,in the illustrated embodiment of the invention. In order to control thepressure in the high side of the system and thereby to maintain the loadon the compressor 3 under a predetermined maximum, the present inventionis provided with an arrangement for introducing gaseous refrigerant intothe second capillary when the pressure Within the high pressure side ofthe system, as indicated by the pressure within the receiver exceeds apredetermined maximum. By the introduction of gaseous refrigerant intothe second capillary 11, the flow of liquid refrigerant through thecapillary is greatly reduced or restricted. For injecting gaseous.refrigerant into the second capillary, there is provided a bypassconduit 13 connecting the intermediate chamber 12 with the upper portionof the receiver 8 where high pressure refrigerant gas not liquified inthe condenser normally accumulates. If the receiver 8 is eliminated andthe storing of liquid refrigerant is performed by the last few coils ofthe condenser 4, then the bypass conduit 13 connects with the condenserat some point ahead of the stored liquid refrigerant, such as ata pointin the first few coils of the condenser. chamber 12 through an openingor port 14 in the bottom The bypass conduit 13 connects with the thepressure on the high side of the system exceeds a predetermined amount.In the illustrated embodiment of the invention, the pressure responsivemeans includes a valve 16 seated in the port 14 and biased into theclosed position to prevent the flow of gas into. the chamber. A weight17, which is arranged to ride in piston-like fashion withinthecylinder-like chamber 18, arranged above the intermediate. chamber 12,biases the valve 16 into the closed position; The weight, of course, isjust sufiicient to prevent opening of. the port by the gas pressureexerted on the face of the valve 16 until such pressure reaches apredetermined maximum. I Other types of flow restrictor valvearrangements could be used for controlling the flow of gaseousrefrigerant through the conduit 13 according to pressures within thereceiver 8. For example, a pressure responsive bellows could be arrangedwithin thethe control arrangement on the total refrigerant flow inthesystem may be more clearly understood when the operation of the systemis considered under the temperature conditions encountered duringutilization of the system in an air conditioning device. ment outdoorair is sometimes blown for cooling purposes over the condenser 4, andthe temperature of the outdoor air, since it fluctuates greatly duringthe summer cooling period, causes the pressure within the condenser andthe high pressure side of the system to vary over a wide range. If somearrangement is not provided for maintaining load conditions below acertain predetermined amount, it is necessary to provide therefrigeration system of the air conditionerwith a compressor motor ofsufiicient power to operate the compressor under the maximum loadconditions which would result from the extreme temperatures encounteredin any part of the country inwhich the conditioner might possibly beused. Thus, the load conditions resulting from an outdoor temperature of120 F., which occurs at times in some Southwestern areas of the country,would require the utilization of a much more powerful motor in relationto compressor displacement, than would be necessary if the system neverhad to be operated under load conditions greater than those existingwhen the outdoor temperature is 100 F. or below.

Also, if such a powerful motor is utilized to drive the.

compressor, then, at all temperatures below 120 F. the motor is unloadedand the potential refrigerating capacity of the system is not madeavailable during most of'the time that it is used. a

In the system of the present invention the valve 16 and weight 17 aredesigned to permit gas into the intermediate chamber when the high sidepressure reaches a predetermined. maximum, such as 300 psi. That is,when the gas pressure in the receiver equals 300 p.s.i., there isexerted against the area of the valve sufficient pressure to overcomethe imposed weight 17 thereby opening the valve to permit flow of gasinto the intermediate chamber 12 at the same pressure as that of thereceiver 8. Flow of high pressure gas into the intermediate chamberraises the pressure of the intermediate chamber 12 to that of Or, forexample, a spring loaded valve.

In such an arrangethe amount of compressed gas fed to the condenser witha corresponding build-up of the liquid refrigerant stored in thereceiver 8, or in the latter stages of the condenser 4 when no receiveris used, which rapidly reduces the pressure in the high pressure side ofthe system. When the pressure in the receiver is reduced below 300 psi,or any desirable predetermined maximum pressure'as determinedbythedesign of the valve 16 and weight 17, then thevalve '16 closes'theport 14 and the liquid refrigerant again begins to flow in the normalmanner through the system.

'From the foregoing, it is apparent that there is provideda controlarrangement for a refrigeration system, such as those employed'in aircooledair conditioning systems, which automatically maintains the highside pressure and the resultant load conditions on the compressor belowa predetermined maximum regardless of the temperatureof the air blownover the condenser of the system.

While in accordance with the patent statutes there has been describedwhat at present is considered to be the preferred embodiment of theinvention, it will be obvious to'those skilled in the art thatvariouschanges and modifi'cations may be made therein without departing fromthe invention and it is, therefore, the aim of the appended claim tocover all such changes and modifications as fall within the true spiritand scope of the invention.

What I' claim as new and desire to secure by Letters Patent of theUnited States is:

A refrigeration system comprising a compressor, a condenser and anevaporator connected in refrigerant flow relationship, a receiver insaid system between said condenser-and said evaporator for storingliquid refrigerant from said condenser, an intermediate chamber in saidsystem between said receiver and said evaporator, a first capillary forconducting liquid refrigerant from said receiver to said intermediatechamber and for creating a pressure drop between said receiver and saidintermediate chamber, a second'capillary for conducting refrigerant fromsaid intermediate chamber to said evaporator and gas-to flow into saidintermediate chamber in response to an increase in pressure in saidreceiver above a predetermined amount whereby gaseous refrigerant isintroduced into said intermediate chamber and thence into said secondcapillary to restrict the flow of liquid refrigerant through said secondcapillary thereby reducing the total refrigerant flow through thesystem.

References Cited in the file of this patent UNITED STATES PATENTS2,807,940 'Urban O ct. ,1, 1957 Hubbard Nov. 9', 1942'

